The complete guide to cloud PBX.
What a cloud PBX is, how it differs from the alternatives, and why UK businesses are moving to it.
What is a cloud PBX?
A PBX (Private Branch Exchange) is the system that manages calls within a business — routing them, holding them in queues, offering menus and connecting internal extensions. A cloud PBX does all of this from secure data centres rather than a box on your premises, with calls carried over your internet connection.
The result is a full-featured phone system with no on-site hardware to buy, maintain or replace, managed entirely through a web portal.
Cloud PBX vs traditional and on-premise PBX
A traditional or on-premise PBX is physical hardware you own, maintain and eventually replace, tied to ISDN lines that are being switched off. A cloud PBX removes all of that: no capital outlay, no maintenance visits, instant changes and updates included.
Against self-hosted software like 3CX, the difference is management — with 3CX you host and patch it yourself; with our cloud PBX, we run and support the whole thing for you.
Cloud PBX vs hosted VoIP
These terms overlap. Hosted VoIP describes the internet calling; cloud PBX describes the call-management intelligence. In practice they’re delivered together as one service — so you don’t need to choose between them.
Cloud PBX for multi-site businesses
If you operate from more than one location, a cloud PBX ties them together under one number plan. Calls between sites are internal and free, staff keep the same extensions wherever they work, and opening a new site just means adding users — no new phone infrastructure required.
Cloud PBX and the PSTN switch-off
Because a cloud PBX already runs over the internet, it’s the natural replacement for systems that depend on the PSTN and ISDN lines being retired by 2027. Moving now both future-proofs you and usually reduces your monthly cost.
How much does a cloud PBX cost?
Cloud PBX is priced per user per month, often from around £5, with no large upfront cost. You scale users up and down on demand, and there’s no separate maintenance contract or line rental.
Eight signs you've outgrown basic VoIP
Basic hosted VoIP answers calls; a cloud PBX runs a call operation. You need the PBX layer when the signs stack up: 1) callers complain about ringing out or bouncing between people; 2) more than one team should answer different things (sales vs support); 3) you've no idea how many calls you missed last week; 4) busy periods mean engaged tones; 5) transfers are shouted across the office; 6) out-of-hours is a personal mobile and hope; 7) you're opening a second site; 8) a manager has asked "can we see call stats?" and the answer was no. Three or more, and queues, menus and reporting will pay for themselves inside a quarter. One or none — honestly, basic hosted VoIP is all you need today, and the upgrade path later is a licence change, not a new system.
Cloud vs on-premise: total cost over five years
The on-premise comparison only looks close in year one. Over five years the shape is stark:
| Cost line | Cloud PBX | On-premise PBX |
|---|---|---|
| Upfront | Little to none | Hardware, licences, installation — the big cheque |
| Years 1–5 running | Predictable per-user monthly, updates included | Annual maintenance contract, licence renewals, engineer callouts |
| Growth | Add a user in minutes at the same rate | Capacity cards, licence tiers, sometimes a fork-lift upgrade |
| Year 5 | Still current — the platform updated itself | End-of-life decision looming; residual value near zero |
| The outage | Calls re-route automatically; site problems don't touch the platform | The box is the single point of failure — and it's in your building |
The one scenario where on-prem still computes: you recently paid the big cheque. Then the right move is sweating the asset to its next maintenance renewal — that invoice is typically the moment cloud pays from day one. Full comparison: cloud vs on-premise PBX.
What actually differs between cloud PBX providers
Feature lists have converged — everyone claims queues, menus and apps. What actually differs: routing depth (can it express your real rules — time conditions inside queues, overflow chains, per-DDI behaviour — or just the brochure basics?); the portal (can your office manager change a greeting in two minutes, or is every tweak a ticket?); reporting (real answered/missed/wait data per queue, or a vanity dashboard?); integrations (your CRM, your industry software, an API for the weird thing you'll want next year); and who configures it (a provider who designs your call flows with you, versus a login and good luck). Ask each contender to build one of your actual call flows in the demo — the ones who can't do it live can't do it after you've signed either.
Features that matter daily vs features that demo well
Every cloud PBX demo dazzles — and six months in, most businesses use a stable core while the showroom features gather dust. The daily-use core, in honest order: voicemail-to-email (used constantly, appreciated forever), the mobile app (the feature that changes behaviour), queues and sensible menus (the customer-facing difference), time-based routing (set once, quietly perfect), and the missed-calls report (the one managers actually open). The demo-well tier — video built-in, chat channels, presence walls, AI meeting notes — is genuinely useful for some teams and pure shelfware for others; buy it when a named person asks for it, not because the slide was impressive. And one feature is reliably undersold in demos because it's unglamorous: the audit trail of who changed what in the call flows — the thing you'll want desperately the morning routing mysteriously breaks. Weight your evaluation toward the boring core and the portal that manages it; that's where the next three years of value live.
Frequently asked questions
Is cloud PBX the same as hosted VoIP?
They’re two sides of one service — we deliver both together as a complete phone system.
Do I need any hardware?
No on-site PBX — just handsets, computers or mobiles, whichever suits you.
Can it handle multiple sites?
Yes — one number plan across all locations with free internal calls.
Is it switch-off ready?
Yes — it already runs over the internet, so it’s unaffected by the 2027 PSTN retirement.
What's the minimum business size for a cloud PBX?
There isn't a hard one — but the PBX layer earns its keep from roughly 5–10 people or the first moment you have departments. Smaller teams should start on hosted VoIP and upgrade when the self-test says so; it's a licence change, not a migration.
Can we keep our existing handsets on a cloud PBX?
Usually — mainstream IP handsets reprovision onto the new platform, and we audit yours before quoting so nothing is replaced unnecessarily.
Who builds and maintains our call flows?
We design the first version with you as part of setup, then either train your team to self-serve in the portal or keep tuning it for you — most clients do a mix.
Can we see and test the system before signing?
Insist on it — and make the demo build one of your real call flows live. It's the single most revealing test of both platform and provider.
How disruptive is moving from an old PBX?
Minimal when staged: the cloud system is built and tested in parallel, numbers port on an agreed day in minutes, and the old box stays racked until you're satisfied. The calm version is the normal version.
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